Project Summary/Abstract Abstract: A key aspect of cell and tissue morphogenesis is regulation of the actin cytoskeleton. The actin cytoskeleton is a fundamental cellular scaffold which dictates cell morphology and multiple important dynamic cell processes such as cell migration. Cofilin is a member of a family of important actin assembly-regulatory proteins. Inactivation of cofilin-1 in mice results in several neural developmental anomalies such as impaired neural tube closure and defective neural crest migration. Similar abnormalities are associated with human congenital diseases. Multiple signals converge to regulate patterning of the nervous system. As is the case for cofilin, previous studies have implicated essential roles for Wnt signaling in neural development. The means by which these factors coordinately control patterning of the nervous system is not known. A role for cofilin in non canonical Wnt signaling has recently been established in flies. However it is not known whether cofilin is involved in Wnt signaling in vertebrates. This proposal aims to identify regulatory mechanisms governing cofilin and actin dynamics during neural crest migration. We hypothesize that non canonical Wnt signaling dictates cell morphology, actin cytoskeleton architecture and polarized cell migration through regulation of cofilin activity. Using the chick as a model system, we will determine the precise requirements for Wnt signaling and cofilin in neural crest patterning. We will examine the role of cofilin and Wnt signaling on neural crest cell behavior and cytoarchitecture during migration using 4D fluorescence confocal microscopic live cell imaging of whole embryos and neural crest explant cultures. Dynamic F-actin remodeling will be assessed by techniques such as fluorescence recovery after photobleaching. Furthermore, by use of commonly utilized biochemical procedures we will establish the means by which Wnt signaling controls cofilin function and neural crest migration. These studies are necessary to gain a better understanding of the mechanisms that govern neural development and will help to facilitate preventative or therapeutic measures for congenital human diseases resulting from anomalous neural patterning. The studies proposed here represent a foray into a new avenue of neuroscience research for the principal investigator. The principal investigator is a committed scientist who is seeking this career development award to aid in the acquisition of new skills in the use of animal model systems for studying neural patterning. It is anticipated that the skills acquired through this award will contribute to the applicant's ultimate career goal of becoming a productive independent investigator in neuroscience research. Future research as an independent investigator will revolve around the study of embryologic development of the nervous system and related human diseases. The animal model systems developed during the period of the award will provide a platform for future investigation. Specific career enhancement objectives during the proposed period of this award are 1) increased knowledge and expertise in the area of developmental neuroscience; 2) increased knowledge and skills in the use of the chick and other organisms as animal model systems to study development of the nervous system during embryogenesis; 3) increased knowledge and skills in various live cell microscopy methodologies; 4) improved teaching and mentorship skills. These skills will be acquired through both formal and informal training exercises. Structured training activities will include enrollment in specific courses and technique workshops. These career development objectives will be achieved under the supervision of three co-mentors who are all renowned expert neuroscientists and excellent mentors. The sponsoring institution has committed full support in assisting the applicant achieve his stated career development objectives. The institution offers amenities such as a vibrant local neuroscience community with diverse expertise, an imaging facility with state of the art microscopy equipment, and all other necessary tools to support successful completion of the applicant's research aims and career development plan.